Solid state devices are typically formed by depositing, growing, patterning and etching a series of layers. Different layers may comprise conducting, semiconducting or insulating material. Typically, such layers are anisotropically etched to form the various elements of a solid state device. Anisotropic etches may also be used to remove layers without damaging previously formed elements. An anisotropic etch may refer to a dry etch. A dry etch may be a reactive ion etch (RIE) or an argon sputtering operation. A problem with anisotropic etches, however, is that they often leave a residual layer of byproducts. These byproducts may be contaminants that interfere with later semiconductor processing such as silicide formation.
As a result of that, a wet etch is therefore combined to the anisotropic etching operation. A wet etch may be performed subsequent to the anisotropic etching operation to remove the unwanted residual layer. Unfortunately, in addition to the byproducts, a chemical wet etching agent may also remove important parts that should not be removed. Therefore, a novel mechanism to mitigate aforementioned issues during etching operation has become an urgent need in fields pertinent to semiconductor manufacturing industry.